Effect of two thermal regimes on the muscle growth dynamics of sea bass larvae,Dicentrarchus labrax L

Muscle growth was studied in larvae of sea bass, Dicentrarchus labrax L., reared at two temperatures: real ambient temperature ( congruent with 15 degrees C during vitelline phase and increased gradually) and 19 degrees C from fertilization until the end of larval development. Muscle cellularity, body length and body weight were measured. Early temperature influenced larval development and so, pre-larval phase finished earlier at 19 degrees C than at ambient temperature (4 and 6 days, respectively). Temperature also affected muscle growth such that at hatching and at mouth opening hypertrophy of muscle fibres was greater at 19 degrees C (P < 0.05), whereas hyperplasia was similar in both groups. After 25 days, the cross-sectional area of the white muscle was greater at 19 degrees C (P < 0.05), which was mainly associated with a higher proliferation of new white muscle fibres. At this stage the body length was also higher at 19 degrees C. Metamorphosis finished earlier in fish reared at 19 degrees C (52 days) than at natural temperature (82 days). At this developmental stage body length and cross-sectional area of the myotome were similar in both groups. However, muscle cellularity differed between groups. Thus, hypertrophy of muscle fibres was higher in fish reared at ambient temperature (P < 0.05), whereas proliferation of new muscle fibres was higher at 19 degrees C (P > 0.05).     

Effect of nutritional supplementation upon pregnancy rates of goats under semiarid rangelands and exposed to the male effect

The aim of this study was to evaluate possible effects of improved protein and energy diet upon reproductive outcomes of adult goats under marginal rangeland grazing conditions and exposed to the male effect during the anoestrous-dry season. Adult goats (Nubian × Criollo, nonpregnant, nonlactating, n?=?160, 22° 50' N, 100° 59' W, 1,653?m) were randomly divided in two experimental groups: Control (CG; n?=?80) and Supplemented (SG; n?=?80). Both CG and SG goats were kept together during the day for ranging a semiarid rangeland while separated accordingly at night. SG goats were individually supplemented [400?g?kg(-1)?day(-1)?; 14% CP and 2.92 Mcal DE kg(-1)] during a 30-day period. Thereafter, both the CG [35.5?±?0.94?kg LW, 1.95?±?0.06 U, body condition score (BCS)] and the SG [39.5?±?0.94?kg LW, 2.29?±?0.06 BCS] were exposed to adult males (Nubian, n?=?4, two per group) of proven libido and fertility and kept together at night (1700-0900) during a 42-day experimental breeding period. At the beginning of the breeding period, both LW (P??0.05), respectively. Results suggest that nutritional supplementation and the male effect were able to successfully invoke neurophysiological pathways to increase ovarian activity and to promote a uterine milieu prone to the establishment of pregnancy during the anoestrus season. However, the increased abortion rates observed in the study occurred irrespective of the nutritional regime offered during the premating stage. Therefore, there is a need to align the last third of gestation to the onset of the grazing season in order to increase reproductive and economic efficiency in those rangeland-based marginal goat production systems.     

Assessment of dexmedetomidine/ketamine anesthesia in golden-headed lion tamarins (Leontopithecus chrysomelas)

OBJECTIVE: To compare the anesthetic and cardiovascular effects of dexmedetomidine/ketamine combinations in golden-headed lion tamarins. STUDY DESIGN: Prospective blinded randomized study. ANIMALS: Six healthy golden-headed lion tamarins, three males and three females were studied (mean body weight +/- SD = 0.498 +/- 0.054 kg). METHODS: The animals were given one of the dexmedetomidine/ketamine combinations (0.005/10, 0.01/10, and 0.01/5 mg kg(-1) IM; treatments 5D/10K, 10D/10K, and 10D/5K, respectively) on three successive occasions. Time to sedation and recumbency, as well as anesthesia, standing, and walking times were recorded. Heart and respiratory rate, arterial blood pressure, hemoglobin saturation, and rectal temperature were recorded during anesthesia. Sedation, muscle relaxation, and auditory response were evaluated after drug administration. RESULTS: Heart rate decreased after two combinations (10D/5K and 10D/10K). Respiratory rate and rectal temperature progressively decreased in all the treatments. Arterial blood pressures were maintained in 5D/10K and 10D/5K treatments and decreased after 10D/10K administration. There were no differences in sedation and recumbency time between the treatments, but anesthesia time was significantly longer in treatment 10D/10K (67.80 +/- 13.30 minutes) compared to treatments 10D/5K (44.54 +/- 8.25 minutes) and 5D/10K (30.60 +/- 6.80 minutes). Standing time was shorter in treatment 10D/10K (11.13 +/- 10.01 minutes) than in treatments 5D/10K (18.20 +/- 10.03 minutes) and 10D/5K (19.12 +/- 14.55 minutes), and walking time was longer in treatment 5D/10K (20.00 +/- 12.46 minutes) compared with treatments 10D/10K (16.00 +/- 3.43 minutes) and 10D/5K (12.40 +/- 5.02 minutes). Anesthetic quality was significantly better 5 and 15 minutes after treatments 10D/10K and 10D/5K than after treatment 5D/10K. Analgesia scores were higher after administration of 10D/10K than after the 5D/10K treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Dexmedetomidine/ketamine is useful for chemical immobilization of golden-headed lion tamarins, but bradycardia and hypotension warrant close monitoring.     

Short-wave solar radiation level willingly tolerated by lactating Holstein cows in an equatorial semi-arid environment

The amount of short-wave solar radiation willingly tolerated by lactating Holstein cows on pasture was determined in an equatorial semi-arid environment. The study was carried out on a dairy farm located in Limoeiro do Norte, CE, northeastern Brazil. The observed behaviours were as follows: grazing, under the sun, under the shade, standing, lying, ruminating, idling and wallowing in the water. The behaviours were recorded using instantaneous scan sampling at regular intervals of 15 min from 0600 to 1800 hours over 5 days. On all sampling days, the meteorological variables, including local short-wave solar radiation (R _S-W, W m^?2), were recorded. The R _S-W data were divided into five levels. The sun exposure was more frequent under low (100 %) and moderately low (97 %) levels, when R _S-W remained below 500 W m^?2. The grazing was more intense under low (100 %) and moderately low (93 %) levels. Above 500 W m^?2, the grazing time significantly decreased (11 %). The cows avoided grazing under high (0 %) and very high (0 %) levels, when R _S-W exceeded 700 W m^?2. The ruminating behaviour was more frequent under high (33 %) and very high (37 %) levels, in which the highest averages of R _S-W were recorded (815 and 958 W m^?2, respectively). The standing posture was more frequent under low (100 %) and moderately low (97 %) levels. Therefore, the critical R _S-W level that motivates cows to stop grazing and seek shade was in the interval between 500 and 700 W m^?2.     

Effect of nutrition during calfhood and peripubertal period on serum metabolic hormones, gonadotropins and testosterone concentrations, and on sexual development in bulls

The objective of the present study was to characterize the effects of nutrition on circulating concentrations of metabolic hormones, gonadotropins, and testosterone during sexual development in bulls. Nutrition regulated the hypothalamus-pituitary-testes axis through effects on the GnRH pulse generator in the hypothalamus and through direct effects on the testes. Pituitary function (gonadotropin secretion after GnRH challenge) was not affected by nutrition. However, nutrition affected LH pulse frequency and basal LH concentration during the early gonadotropin rise (10-26 weeks of age). There were close temporal associations between changes in insulin-like growth factor-I (IGF-I) concentrations and changes in LH pulse frequency, suggesting a role for IGF-I in regulating the early gonadotropin rise in bulls. The peripubertal increase in testosterone concentration was delayed in bulls with lesser serum IGF-I concentrations (low nutrition), suggesting a role for IGF-I in regulating Leydig cell function. Serum IGF-I concentrations accounted for 72 and 67% of the variation in scrotal circumference and paired-testes volume, respectively (at any given age), indicating that IGF-I may regulate testicular growth. Bulls with a more sustained elevated LH pulse frequency during the early gonadotropin rise (high nutrition) had greater testicular mass at 70 weeks of age relative to the control group (medium nutrition), despite no differences in metabolic hormone concentrations after 26 weeks of age. Therefore, gonadotropin-independent mechanism regulating testicular growth might be dependent on previous gonadotropin milieu.     

Temperature effect on muscle growth of the axial musculature of the sea bass (Dicentrarchus labrax L.)

In order to determine the temperature effect on the axial muscle growth of sea bass, a stock of larvae was subjected to the following incubation and cultivation temperatures, respectively: 15 degrees C/ambient, 15/17 degrees C, 17 degrees C/ambient and 17/17 degrees C. In all groups the cross-sectional area of white and red muscles and the number and average area of the white and red muscle fibres were quantified. Results showed that the embryonic period, pre-larval phase and the end of metamorphosis were accelerated at higher temperatures. During the endogenous feeding period, muscle growth took place by fibrillar hypertrophy, and was not influenced by the temperature. Thereafter (external feeding) muscular hyperplasia began, and growth of all the muscular parameters was favoured by the effect of high incubation and cultivation temperatures, with the latter having higher influence. High incubation temperature had an slight effect on muscle growth and body length, which was only observed from 15 days. Metamorphosis finished at 3 +/- 0.4 cm in all the larvae, but this length was earlier reached at higher temperatures. At 120 days, the largest growth was obtained in the larvae maintained at a higher temperature.     

Correlation of magnetic resonance images with anatomic features of the equine tarsus

OBJECTIVE: To correlate anatomic features of the equine tarsus identified in plastinated sections with images obtained via magnetic resonance imaging (MRI). ANIMALS: 4 horses. PROCEDURE: MRI (1.5-Tesla magnet) of the tarsus was performed on the pelvic limbs of 4 clinically normal horses following euthanasia. After imaging, tarsocrural joint spaces and vasculature were injected with colored latex. Sagittal and transverse sections of the tarsi were plastinated to facilitate interpretation of MR images. RESULTS: Relevant anatomic structures were identified and labeled on the plastinated tissue slices and corresponding MR images. Results indicated high correlations between MRI findings and those of plastinated sections. CONCLUSIONS AND CLINICAL RELEVANCE: The data obtained provided certain reference standards for normal anatomic structure sizes and positions in the equine tarsus. This information may aid future physiologic or clinical studies of this joint.     

Crude protein fractions in common vetch (Vicia sativa L.) fresh forage during pod filling

Crude protein (CP) of forages can be separated into fractions of differentiated abilities to provide available amino acids in the lower gut of ruminants. This knowledge is critical to develop feeding systems and to predict animal responses. We have measured during two growing seasons (1996 to 1997 and 1997 to 1998) the CP fractions of common vetch fresh forage with the objective being to assess the influence of maturity on concentration of CP fractions (as a percentage of total CP) and fraction yields. Fraction B2, which represents true protein of intermediate ruminal degradation rate, was the largest single fraction in common vetch forage (about 40% of CP across seasons and maturity stages). Soluble fractions (A plus B1) were less than 50% of total CP while the unavailable fraction C ranged from 4 to 8% of total CP. As a result, the remaining fraction B3 (true protein of very low degradation rate) only represented 2 to 9% of total CP. Concentration and yield of fraction B3 increased (P < 0.05) from flowering to pod-filling. Results showed that undegraded dietary protein represented a small proportion of total CP in common vetch forage. Moving the harvesting stage from flowering to the pod filling phase allowed for greater yield of undegraded dietary protein.